(1) Field of the Invention
The present invention relates to a sheet loading device that transports and loads a plurality of recording sheets, one by one, onto a tray included therein and a post-processing apparatus including the sheet loading device.
(2) Description of Related Art
Recently, there are many cases where a post-processing apparatus is attached to and is used in combination with an image forming apparatus such as a copier. Such a post-processing apparatus performs staple processing of stapling recording sheets output from an image forming apparatus and/or other types of processing.
Such a post-processing apparatus includes a sheet loading device that transports and loads a plurality of recording sheets output from an image forming apparatus, one by one, onto a tray included therein. Further, a post-processing apparatus equipped with such a sheet loading device executes staple processing with respect to recording sheets having been loaded onto a tray included therein by utilizing a staple unit included therein. More specifically, such a post-processing apparatus executes staple processing when the number of recording sheets having been loaded onto a tray reaches a specific number specified by a user.
As already explained above, a sheet loading device transports recording sheets one by one onto a tray. Here, problems may arise if a curl is formed on one or more recording sheets already loaded on the tray. When a curl is formed on a recording sheet already loaded on the tray, a rear end of the curled recording sheet may depart from a surface of the tray and block a transport path along which recording sheets are transported to the tray. This leads to recording sheets newly transported to the tray being bent since the rear end of the curled recording sheet departing from the surface of the tray collides with the newly transported recording sheets. In addition, when a curl is formed on a recording sheet that is already loaded on the tray, the order in which recording sheets are loaded onto the tray may be undesirably altered since newly transported recording sheets may slip beneath the curled recording sheet.
So as to provide a measure for preventing such a problem from taking place, Japanese Patent Application Publication No. 2009-120330 (hereinafter referred to as “Patent Literature”), for example, discloses a method where the following procedures are sequentially executed: (i) driving a pressing member so as to press a rear end portion of a recording sheet already loaded on a tray against a sheet loading surface of the tray; (ii) driving a claw member and causing the claw member to engage with the rear end portion of the recording sheet already loaded on the tray so as to restrict the rear end portion from departing from the sheet loading surface; and (iii) causing the pressing member to recede so as to prepare for transportation of a subsequent recording sheet.
Patent Literature indicates that the above-described method realizes: (i) restricting the rear ends of the recording sheets loaded on the tray by driving the claw member; (ii) definitely inhibiting the rear end portions of the recording sheets loaded on the tray from departing from the sheet loading surface; and (iii) thereby ensuring that newly transported recording sheets are smoothly and appropriately loaded onto the tray.
However, according to the method disclosed in Patent Literature, the pressing member and the claw member are driven by separate driving mechanisms, each of which is driven by a separate, independent drive source, partially owing to the pressing member and the claw member being configured to apply pressure on the recording sheets at different, respective timings. This is problematic in that an increase is brought about in the cost of a device performing such a method.